pthread: add const to AVCodec pointers

Signed-off-by: Mans Rullgard <mans@mansr.com>

libavcodec/pthread.c

@@ -357,7 +357,7 @@ static attribute_align_arg void *frame_worker_thread(void *arg)
     PerThreadContext *p = arg;
     FrameThreadContext *fctx = p->parent;
     AVCodecContext *avctx = p->avctx;
-    AVCodec *codec = avctx->codec;
+    const AVCodec *codec = avctx->codec;
 
     while (1) {
         if (p->state == STATE_INPUT_READY && !fctx->die) {
@@ -517,7 +517,7 @@ static int submit_packet(PerThreadContext *p, AVPacket *avpkt)
 {
     FrameThreadContext *fctx = p->parent;
     PerThreadContext *prev_thread = fctx->prev_thread;
-    AVCodec *codec = p->avctx->codec;
+    const AVCodec *codec = p->avctx->codec;
     uint8_t *buf = p->avpkt.data;
 
     if (!avpkt->size && !(codec->capabilities & CODEC_CAP_DELAY)) return 0;
@@ -720,7 +720,7 @@ static void park_frame_worker_threads(FrameThreadContext *fctx, int thread_count
 static void frame_thread_free(AVCodecContext *avctx, int thread_count)
 {
     FrameThreadContext *fctx = avctx->thread_opaque;
-    AVCodec *codec = avctx->codec;
+    const AVCodec *codec = avctx->codec;
     int i;
 
     park_frame_worker_threads(fctx, thread_count);
@@ -777,7 +777,7 @@ static void frame_thread_free(AVCodecContext *avctx, int thread_count)
 static int frame_thread_init(AVCodecContext *avctx)
 {
     int thread_count = avctx->thread_count;
-    AVCodec *codec = avctx->codec;
+    const AVCodec *codec = avctx->codec;
     AVCodecContext *src = avctx;
     FrameThreadContext *fctx;
     int i, err = 0;